Cheetah's lunge/pounce mobility is her great strength. The low profiling is part of her design and her pounces require a lot of thought to be useful -- if you YOLO you get punished. That execution should be rewarded. Her f3 is the best in the game, probably, but it's also just about her only way to advance safely.
She is balanced by having the following flaws:
- Almost all her strings have very punishable gaps
- No real neutral game to speak of: no forward-advancing special, no good advancing strings or normals, stubby arms
- No projectile
- No real chip
- Divekick is punishable
- Wake-up is full combo punishable
- Poor MB roll versus the rest of the cast
- Highly meter-dependent for damage unless you have trait
She's good, don't get me wrong! Solid character. But she is not OP by any means. Very high-risk/high-reward. You just need to learn the matchup if you're having trouble punishing her, because she's very punishable.
I play Cheetah and Canary, and if you asked me which of those rushdown mix characters you should really be worried about, Cheetah would not be my answer.